Article pubs.acs.org/JAFC
Relation between Particle Size and Carotenoid Bioaccessibility in Carrot- and Tomato-Derived Suspensions Katlijn R. N. Moelants, Lien Lemmens, Marijke Vandebroeck, Sandy Van Buggenhout, Ann M. Van Loey, and Marc E. Hendrickx* Laboratory of Food Technology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Department of Microbial and Molecular Systems (M2S), KU Leuven, Kasteelpark Arenberg 22, PB 2457, 3001 Leuven, Belgium ABSTRACT: To study the effect of particle size on the relative all-E-β-carotene and all-E-lycopene bioaccessibility in carrot- and tomato-derived suspensions, respectively, an in vitro digestion approach including oil was used. Adding olive oil (2%) during digestion, especially as an oil-in-water emulsion, resulted in a substantial increase in carotenoid uptake in the micellar phase. Carotenoid bioaccessibility decreased with average particle size. Only particles smaller than an individual cell resulted in high bioaccessibility values, pointing out the importance of the cell wall as the main barrier for carotenoid uptake. The relation obtained between particle size and bioaccessibility was used to predict the carotenoid bioaccessibility in carrot- and tomatoderived purées. These predictions indicated that carotenoid bioaccessibility in plant-based food suspensions is not only determined by the cell wall integrity (related with particle size) but is also affected by interactions between the structural compounds of the complex food matrix. KEYWORDS: bioaccessibility, carotenoids, particle size, carrot, tomato, oil emulsion
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INTRODUCTION Fruits and vegetables are often processed into plant-based food suspensions such as soups, juices and purées. During and certainly after the production process, these suspensions should meet certain specifications, among others microbiological safety and high nutritional quality. To obtain plant-based food suspensions with a high nutritional quality, not only the nutrient concentration (reflecting the amount of nutrients present) but even more the nutrient bioaccessibility is important.1 In order to be accessible for absorption in the gut, the nutrients have to be released from the food matrix.2 Nutrient bioavailability additionally includes nutrient absorption, metabolism, tissue distribution and bioactivity.1 This means that a prerequisite for nutrient bioavailability is its bioaccessibility. Nutrient bioaccessibility is commonly determined by in vitro methods simulating the human digestion3,4 and is assumed to be a good starting point for estimating nutrient bioavailability.5 In this study, carotenoids were considered as micronutrients for the evaluation of the nutritional quality of carotenoidcontaining plant-based suspensions. Besides their differences in chemical structure, all-E-β-carotene and all-E-lycopene were selected because they are found in many fruits and vegetables. These pigments are known to have antioxidant activity, and their consumption may protect against cancer or cardiovascular diseases.6,7 Carotenoid bioaccessibility and bioavailability are affected by both exogenous and endogenous factors, combined in the term “SLAMENGHI”: Species of carotenoids, Linkage at molecular level, Amount of carotenoids, Matrix, Effectors, Nutrient status, Genetics, Host-related factors and Interactions among these variables.8−10 In this study, the effect of the food matrix and structure in which the carotenoids are incorporated on the carotenoid bioaccessibility was investigated. An in vitro digestion approach including oil was used. Since carotenoids © 2012 American Chemical Society
are very lipophilic molecules, transfer to mixed micelles during the digestion is a precondition for absorption in the intestinal tract. 11 The presence of fat can increase carotenoid solubilization in mixed micelles and, therefore, oil addition to a plant-based food suspension can have an important effect on the carotenoid bioaccessibility. Several studies demonstrated the beneficial effect of oil on carotenoid bioaccessibility.12−14 To mimic the emulsifying process as occurring in the gastrointestinal tract, oil was also added as an oil-in-water emulsion during in vitro digestion.15 The latter is a rather new approach, which so far has not commonly been used in the context of in vitro carotenoid bioaccessibility studies. Previously, Tydeman et al.16 sought to mimic in vitro the dietary emulsion produced during digestion in terms of droplet size and composition. They reported an increase in carotene uptake in the oil phase when an oil emulsion was used instead of bulk oil, and transfer of carotenoids to micelles was not specifically investigated. In the first part, the relative all-E-β-carotene and relative allE-lycopene bioaccessibility in carrot- and tomato-derived products, respectively, with varying particle size were determined in order to identify the relation between the particle size, resulting from tissue disintegration, and the carotenoid bioaccessibility in two different food matrices. In contrast to most of the previous studies investigating the importance of the cell wall structure and particle size for carotenoid bioaccessibility in real, complex plant-based food suspensions,13,16−19 the current study used specific model suspensions, composed of isolated particle size fractions, to Received: Revised: Accepted: Published: 11995
August 13, 2012 November 15, 2012 November 16, 2012 November 16, 2012 dx.doi.org/10.1021/jf303502h | J. Agric. Food Chem. 2012, 60, 11995−12003
Journal of Agricultural and Food Chemistry
Article
Table 1. Composition of the Reconstituted Purées Assembled from Several Particle Size Fractions with Different Particle Sizes and Particle Size Distributions of Carrot and Tomato Purées, Obtained by Blending (Followed by High-Pressure Homogenization at 20 MPa), Calculated as the Mass Percentage of Each Particle Size Fraction Collected after Wet Sievinga mass percentage of each particle size fraction (wt %) 500−1000 μm 250−500 μm 125−250 μm 40−125 μm
